Timebomb jobs: the activities most likely to delay your project

Hidden in the final 20% of some construction work streams are ‘timebombs’ – jobs that take far longer than the activity’s planned duration. Planning for that could help projects cross the finish line on time, new research from Buildots shows.

Sprinkler branches, steel frame system (SFS) walls, and raised access flooring top the list of what Buildots identified as the longest-tail activities. It took these jobs nearly twice as long as planned to finish the last 20% of their scope.

Buildots drew its conclusions from analysis of 102 projects in different countries, including residential, office, education, industrial, healthcare and commercial. To avoid small-sample conclusions, all work streams analysed had at least eight weeks of recorded progress data from a minimum of eight projects.

A total of 40 activity types and 1,077 project-activity combinations met this threshold.

Amir Berman, Buildots’ vice-president of industry transformation, said the pattern was consistent enough to suggest the phenomenon was built in.

“While we don’t have all the answers, we noticed that the longest-tail activities tend to be trades that depend on access to many locations across a project,” he said.

“For example, sprinkler branches need to reach every zone and floor. Floor tiling covers every room. Ceiling framing spans every corridor. Once the main push is done, finishing these activities requires working through small, scattered, hard-to-access pockets of remaining scope. Those pockets are slow.”

The 40 activities studied varied significantly in how long the final 20% of work takes. In 44% of cases, the final 20% of the job as planned actually consumed 30% or more of the job’s total duration. In 24% of cases, it took 40% or more, while in 12% of cases, it took 50% or more.

Unlike the “top offenders”, some jobs are schedule helpers, taking less than 20% of the job’s calculated duration to complete the final 20% of its scope.

The stars here are drywall closure (11% of calculated duration), fire alarms (16%), wall and ceiling mist coating (17%) and dryline ceiling boarding (19%).

Berman said these short-tail activities tend to be either discrete installations like doors, fire alarms and light fixtures, or finishing passes over already-prepared surfaces.

“Once the preparation work is done, these trades can move fast because their remaining scope isn’t geographically scattered in the same way,” he said.

“Schedules built on a single, assumed profile simply don’t match the physics of a modern job site. The closer our planning gets to activity-specific realism, the more honest and achievable our expectations become.”